Drive and stop apparatus for sewing machines



Sept. 12, 1961 M. SCHWAB 2,999,575

DRIVE AND STOP APPARATUS FOR SEWING MACHINES Filed April 15, 1953 6 Sheets-Sheet 1 I NVE NTOR ATTORNEY Sept. 12, 1961 M. SCHWAB 2,999,575

DRIVE AND STOP APPARATUS FOR SEWING MACHINES Filed April 15, 1953 6 Sheets-Sheet 2 INVENTOR Max $c/7Wab ATTORNEY Sept. 12,- 1961 M. scHwAB 2,999,575

DRIVE AND STOP APPARATUS FOR SEWING MACHINES Filed April 15, 1953 6 Sheets-Sheet 5 INVENTOR ATTORNEY M. SCHWAB Sept. 12, 1961 DRIVE AND STOP APPARATUS FOR SEWING MACHINES Filed April 15, 1953 6 Sheets-Sheet 4 INVENTOR Mix SCfin db 2% ATTORNEY Sept. 12, 1961 M. SCHWAB 2,999,575

DRIVE AND STOP APPARATUS FOR SEWING MACHINES Filed April 15. 1953 6 Sheets-Sheet 5 INVENTOR BY 2W ATTORNEY Sept. 12, 1961 M. SCHWAB 2,9

DRIVE AND STOP APPARATUS FOR SEWING MACHINES Filed April 15, 1953 6 Sheets-Sheet 6 INVENTOR. Max 63% Wd BY ZM ZW ATTORNEY United States Patent 2,999,575 DRIVE AND STOP APPARATUS FOR SEWING MACHINES Max Schwab, Verl. Schetfelstr. 55, Schwetzingen, Baden, Germany; Olga Brnnizilde Schwab, ne Bonner, sole devises of said Max Schwab, deceased Filed Apr. 15, 1953, Ser. No. 349,061 Claims priority, application Germany Apr. 17, 1952 9 Claims. (Cl. 192-146) The present invention relates to an electric power source for sewing machines which enables the operator to stop the machine with the needle bar in a pre-elected dead position.

More particularly, the invention relates to an electric power source comprising a motor and a rotatably arranged coupling and brake system driven by the motor. According to the invention, the motor and the brake are operatively connected with each other by a magnetic clutch the disengagement of which, although initiated by the operator, is governed by that part of the power source which turns at a constant speed of rotation.

As will be seen from the description, the brake system can be arranged outside of, or integrally with, the power supply. Either arrangement is compact and accessible, and is easy to install without requiring special skill. The operating voltage for the magnetic clutch can be drawn from the starter of the motor. If it is desirable to use direct current, a rectifier can be attached to the power source. The task of wiring during installation is eliminated, because the power source can be furnished completely wired. If means are to be supplied for a lowvoltage illumination, the necessary current can be taken from the starter of the motor.

The nature and purpose of the invention will be readily understood by referring to the accompanying drawings, in which:

FIG. 1 is a side view, partly sectional, of one embodiment of the invention,

FIG. 2 is a front elevation of this embodiment,

FIG. 3 is a side view, partly sectional, of a modification of the invention,

FIG. 4 is a front view of this modification,

FIG. 5 is a rear elevation of the embodiments shown in FIGS. 1 and 3,

FIG. 6 is a top view of the embodiments shown in FIGS. 1 and 3,

FiG. 7 is a side view, partly sectional, of still another embodiment of the invention, and

FIG. 8 is a schematic illustration of the electric control circuit and the foot control operating this circuit.

Referring more specifically to the drawings, there is shown a motor 1, having a motor shaft 2 which is provided with bearings such as the bearing 3. A coupling disk 4 is attached to the end of the motor shaft, held by the nut 5 and forced to turn with the shaft by means of the feather key e. A coupling lining 7 is fastened to another coupling disk 8, fitted onto a coupling shaft 9 and secured there in position by the nut 10, while the feather key 11 prevents this coupling disk from rotating independently. The coupling shaft is provided with bearings, such as the ball bearings 12 and 13, which are mounted within a bushing 14, the said bushing being arranged to turn and to slide back and forth along the hub 15 of the coupling frame 16. In addition, the coupling shaft carries a brake disk 17 and a driving sheave 18, the latter being the connecting link to the sewing machine. The said coupling frame comprises the stays 19, 20 and 21. Rotatably centered within these stays is the brake drum 22, carrying the brake lining 23 and being secured in position by the shoulder 24 and the screw 25. The brake drum, being crowned with sprockets or a sheave 2,999,575 Patented Sept. 12., 1961 groove 26, by means of a chain or rope 27, is operatively connected to a sprocket wheel or sheave 28, fastened to the end of a gear shaft 29. This gear shaft is situated at the bottom of the motor support housing and is kept from shifting longitudinally by means of the adjustment rings 31 and 32.

At its other end the said gear shaft carries an additional sprocket wheel or sheave 33 which in a similar manner, that is, by means of a chain or rope 34, is operatively connected with a sprocket crown or sheave groove 35 of the part 36 which is the rotatable and oscillating part of a magnetic clutch. This magnetic clutch comprises, in addition, an element 37 which is fixedly attached to the end of the motor shaft 2. The transmission elements 33 and 34- as well as the magnetic clutch are protected by a cowl 38, having the connecting means 39 for the power supply to the magnetic clutch fastened thereto. Mounted within the base 30 is, in addition, a switch 40, comprising two operating levers 41 and 42 which are connected, in any convenient manner, to a foot control of the sewing machine. Depending upon whether a pressure or a higher pressure is exerted against the right side 72b or left side 72a of the said foot control, one of these levers is actuated. For example, the arrangement can be such that, if a pressure or a higher pressure is exerted against the left side of the foot control, the lever 41 is actuated, resulting in a stop of the sewing machine with the needle bar in, say, the highest dead position. Conversely, if the lever 42 is actuated by the operator, the sewing machine will stop, for example, with the needle bar in the lowest dead position. It will be obvious from the description, that adjustments can be made to stop the sewing machine with the needle bar in any desired dead position. For this purpose, there is placed, within the base 30, a short shaft 43, the end of which, extending from the base, carries a spur wheel 44 which furnishes the necessary operative link to one of the main drive shafts of the sewing machine. Also mounted on the said shaft are the friction rings 45, 46 and 47, while attached to the housing of the base, in operative alignment with the friction rings, are the power supply contacts 48, 49 and 50. The friction rings differ from each other in that the friction ring 46 is adapted to supply power to the magnetic clutch during the normal operation of the sewing machine, whereas the friction rings 45 and 47, each having a notch at the periphery, are arranged in such a manner that, whenever one of them attains a certain rotatory position while forming part of the electric circuit, the magnetic clutch is opened the moment the needle shaft of the sewing machine has reached a certain position in its reciprocating movements. In addition, there is mounted, as shown, within the motor base a cut-out switch 51, a fuse 52 for the illumination circuit which may be tapped to the motor winding, a fuse 54 for the circuit of the magnetic clutch and, if required, a rectifier 78. Connecting clamps for the low-voltage illumination are preferably arranged underneath the cover 53 alongside the power contacts for the electric motor.

The moment the engaging lever 55 is actuated, which can be readily accomplished by means of a rod leading from the foot control 72 of the sewing machine, the prongs 56 and 57 of the said lever exert a pressure against the flanges 58 and 59 of a cap 60. This causes an axial shift of the bushing 14 which is fixedly connected with the said cap, until the lining 7 of the coupling disk 8 presses against the disk 4 of the electric motor 1. As a result, the sewing machine, driven from the sheave 18, begins to run. Simultaneously, the brake disk 17 is disengaged from the lining 23 of the brake drum 22. The rotation of the sewing machine causes the spur wheel 44 to turn the shaft 43 and, therewith, the friction rings 45, 46 and 47 which control the magnetic clutch at the rear of the motor. Under the presently described conditions the parts 36 and 37 of the magnetic clutch are in contact with each other. Consequently, the sprocket wheel or sheave 28 is put in motion, by way of the chain or rope 34, the sprocket wheel or sheave 33 and the gear shaft 29', and drives, by means of the chain or rope 27, the brake drum 22. The ratio of transmission is preferable such that the brake drum makes about one turn per second.

As soon as the engaging pressure against the lever 55 ceases and is replaced by a lateral pressure against the foot control, say a pressure which actuates the lever 41 as a result of which the current for the magnetic clutch passes through the notched friction ring 45, the springs 61 and 62 pull the coupling disk 3 with the lining 7 out of contact with the coupling disk 4. At the same time, the brake disk 17 engages the lining 23 of the brake drum 22 which is still rotating. Consequently, the driving sheave 18, being mounted on the same shaft as the brake disk 17, continues its rotation and keeps the sewing machine moving until the needle shaft reaches the desired position. At this moment, or slightly in advance, if necessary, the notch of the friction ring 45 breaks the circuit of the magnetic clutch and the brake drum, the driving sheave, and the sewing machine come to a stop.

The engaging lever 55 is fitted within a rotatable ring 72 which is mounted over a pin 73 and can be turned about the axis of the rotor. A split ring 74 is provided to prevent any axial displacement of the ring 72. The limits of shift in the position of the engaging lever is indicated in FIG. 2. By means of this arrangement the engaging lever attains automatically a position in line with the rod leading from the foot control of the sewing machine.

FiGS. 3 and 4 show a modification of the herein claimed device, characterized by having the brake drum mounted inside the coupling frame 63. The brake lining 64 is attached to the back of the coupling disk 8 and the rotatable brake drum 6 has an internal gear drive 66. This internal gear drive is mated by a pinion 67 mounted on a shaft 68 the bearing 65 of which is fastened to the coupling frame. Mounted at the other end of the shaft 63 is a sprocket wheel 71? which, by means of the chain 71, is linked to the sprocket wheel 28 of the gear shaft 29. The arrangement of the remaining elements is substantially the same as previously described, except that, as shown particularly in FIG. 4, a tension carriage 76, mounted on a rotatable ring '75, is held by the spring 77 and provides the necessary tension for the drive belt of the sewing machine.

FIG. 7 shows a modification of still greater compactness, which is attained by arranging the magnetic clutch between the motor and the driving element of the coupling device. According to this modification, the magnetic clutch can now be incorporated, wholly or in part, into the driving element of the coupling and combine therewith into a mass having the effect of a fly wheel. The rotatable brake is now driven by the electric motor over a gear shaft mounted within the coupling frame, the gears being arranged in an enclosed housing which may be filled with lubricant. The rotatable brake, constructed in form of a drum, encloses the coupling and the magnetic clutch. It is covered by a disk which also covers the afore-rnentioned gear housing.

The numeral 191 indicates an electric motor, while 1&2 refers to a frame containing the coupling, brake and magnetic clutch. Also arranged within the said frame is the shaft 1% which has the rotor 1M- mounted thereon and is rotatably held by the ball bearing 1%. Mounted at the free end of the said shaft is the driving coupling member 106 and immediately thereupon or fitted to the hub thereof is the continuously rotating element 167 of the magnetic clutch. Arranged to freely turn about the said shaft are, furthermore, the driven element 108 of the magnetic clutch and the driving gear wheel 14)? which, together with the driven element 108, can be axially shifted electric motor.

on the hub 110. The numerals 111 and 112 refer to slide bearings which surround the drive shaft and enable the driven part of the magnetic clutch to rotate independently of the shaft. The gear wheel 109 meshes with a gear wheel 1'13 and the shaft 114 of which, being held by the ball bearings 115 and 116 is fitted with a pinion 117 to provide the necessary power transfer to the brake drum 118 which, for this purpose, is fitted with the sprocket ring 119, in operative alignment with the said pinion. The disk 120, being fixedly attached to the brake drum, closes not only the brake drum, but also the housing 121, to the extent as the latter is located within the periphery of the A housing extension indicated by the numerals 122 and 123 provides the necessary enclosure for the gear wheel 113.

Mounted within the brake drum 118, parallel and adjacent to the circular portion thereof, is a driven coupling disk 128, provided with the brake lining 129 on one side and the coupling lining 13h on the other side. The numeral 131 refers to the winding of the magnetic clutch, the iron core 132., 133 of which is fastened to the driving coupling member 106 by means of screws 134, 135 and 136. The dielectric plates 1.37 and 138 provide the necessary space for inserting a wire leading to the winding of the magnetic clutch. Arranged within the brush holder 141 is the brush 142 which constitutes the link between the control mechanism and the winding of the magnetic clutch. The arrangement of the remaining elements is substantially the same as described in connection with the first and second embodiment.

It is, of course, understood, that other changes can be made without impairing the nature of the disclosure.

Having described my invention, what I claim is:

1. An electric power source for a sewing machine which enables the operator to stop the sewing machine with the needle bar in a pre-elected dead position, the said power source comprising an electric motor having an extended motor shaft, mounted on the said motor'shaft a magnetic clutch comprising two adjacent elements, one of the said elements being fixedly attached to the said motor shaft while the other of the said elements is mounted to rotate freely about and to move axially on the said motor shaft in and out of operative contact with the first of the said clutch elements, a coupling frame at one side of the motor, a first coupling element fastened to the end of the said motor shaft within the coupling frame, a coupling shaft mounted within the coupling frame in line with the said motor shaft, a second coupling element mounted on the said coupling shaft to move axially on the said coupling shaft in and out of operative contact with the said first coupling element, spring tension means to keep the said second coupling element out of contact with the said first coupling element, a brake disk fitted to the said coupling shaft to move axially on the said coupling shaft, a brake drum mounted within the said coupling frame about the said brake disk, a sheave for driving the sewing machine attached to the free end of the said coupling shaft, a lever connected at one end to the foot control of the sewing machine and linked at the other end to means counteracting the spring tension and moving the said second coupling element into operative contact with the said first coupling element when the said lever is moved into one position and moving the said brake disk into operative contact with the said brake drum when the said lever is moved into the opposite position, means to rotatably connect the said brake drum to a third shaft arranged parallel to the said first named shafts, and the said third shaft to the said second element of the magnetic clutch, a stub shaft arranged parallel to the afore-named shafts and being adaptable to be o'peratively connected to one of the main drive shafts of the sewing machine, three power contacts arranged adjacent to the said stub shaft, three friction rings mounted on the said stub shaft in operative alignment with the said power contacts, the first of the said friction rings being adapted to supply power to the said magnetic clutch to keep it closed during the normal operation of the sewing machine, the other two of the said friction rings having circuit breaking notches axially offset against each other, and a switch connected to the foot control of the sewing machine which cuts the power passing through the said first friction ring and inserts one of the said other two friction rings in the circuit of the magnetic clutch.

2. An electric power source for a sewing machine according to claim 1, having the said magnetic clutch mounted on the said motor shaft at one side of the electric motor, and having the said first coupling element, together with the elements adjacent to the said first coupling element, arranged at the other side of the electric motor.

3. An electric power source for a sewing machine according to claim 1, in which the said coupling elements are coupling disks, one of them having a coupling lining attached to it.

4. An electric power source for a sewing machine according to claim 1, in which the said second coupling element carries a brake lining on the outside, and the said brake drum, being arranged within the coupling frame in operative alignment with the said second coupling element, has an internal gear drive mated by a pinion which is mounted on a spindle rotatably connected to the said third shaft.

5. An electric power source for a sewing machine according to claim 1, in which a tension carriage is mounted at the front of the coupling frame to act on a drive belt connecting the said sheave with the sewing machine.

6. An electric power source for a sewing machine according to claim 1, in which the said magnetic clutch is arranged on the said motor shaft between the motor and the coupling, a gear wheel is rotatably connected to the driven element of the said magnetic clutch, and a pinion is fastened to the axle of the said gear wheel to engage a sprocket ring fitted onto the said brake drum.

7. An electric power source for a sewing machine according to claim 6, in which the said second coupling element is a disk carrying a coupling lining on the side adjacent to the first coupling element and a brake lining on the side adjacent to the base of the brake drum. 8. An electric power source for a sewing machine according to claim 6, in which the said magnetic clutch and the said coupling are mounted inside of the brake drum and a cover is provided to close the brake drum.

9. An electric power source for a sewing machine ac cording to claim 6, in which a housing is provided for the said magnetic clutch, the said coupling and brake assemblies and the said gear wheel.

References Cited in the file of this patent UNITED STATES PATENTS 2,598,633 Baldwin May 27, 1952 2,692,667 Bliedung et al. Oct. 26, 1954 FOREIGN PATENTS 501,285 Belgium Feb. 28, 1951 509,072 Belgium Feb. 29, 1952 

